Shock-absorbing stopper

Abstract

This shock-absorbing stopper is disposed between a flange part having a first annular surface protruding from the outer circumferential surface of a shaft movable in the axial direction and a protruding part having a second annular surface that protrudes toward the shaft from the inner circumferential surface of a tubular housing accommodating the shaft, the second annular surface being apart from the first annular surface. The shock-absorbing stopper comprises: a metal ring in contact with the first annular surface; an annular shock-absorbing body provided between the metal ring and the second annular surface and joined to the metal ring; and an annular member provided between the shock-absorbing body and the second annular surface and joined to the shock-absorbing body, wherein the shock-absorbing body contains a rubber-like elastic material, the metal ring is an annular flat plate, the annular member is apart from the metal ring and provided on the radially inner side of the shock-absorbing body, and the annular member is of higher rigidity than the shock-absorbing body.

Description

Buffer stopper

[0001] The present disclosure relates to a buffer stopper.

[0002] Steering devices are used in automobiles, for example. The steering device includes a steering wheel operated by the driver, a steering shaft connected to the wheel, a pinion gear coaxial with the steering shaft, and a rack bar with a rack gear that converts the rotation of the gear into axial movement. The movement of the rack bar is transmitted to the wheels via tie rods. The tie rods swing in response to the movement of the rack bar, allowing the wheels to turn in any direction. The rack bar is housed in a rack housing.

[0003] The steering device is provided with a buffer stopper for absorbing impact between the rack bar and the rack housing caused by swinging of the tie rod. For example, a buffer stopper is disclosed in Patent Document 1.

[0004] Fig. 6 is a diagram showing a conventional buffer stopper 9. Fig. 6 shows a rack bar 81, a rack housing 82, and a tie rod 83. The buffer stopper 9 in Fig. 6 has an L-shaped metal ring 91 that contacts the rack bar 81, and a rubber-like elastic body 93 provided between the L-shaped metal ring 91 and the rack housing 82. The provision of the L-shaped metal ring 91 can increase durability against high load input.

[0005] JP 2016-136031 A

[0006] However, the L-shaped metal ring 91 is made up of two parts, one extending along the central axis A of the rack bar 81 and the other extending radially, and occupies a large proportion of the cushioning stopper 9. This results in high costs.

[0007] Fig. 7 shows an example of another conventional buffer stopper 7 designed to reduce costs. The buffer stopper 7 in Fig. 7 has a flat, circular metal ring 71 and a rubber-like elastic body 72 provided between the metal ring 71 and a rack housing 82. By making the metal ring 71 flat, it is possible to reduce costs.

[0008] In the configuration of the buffer stopper 7, the function of cushioning the impact of the rack bar 81 on the rack housing 82 is primarily performed by the rubber-like elastic body 72. In this configuration, if the lubricating grease applied to the rack bar 81 adheres to the gap between the rack housing 82 and the rubber-like elastic body 72, the coefficient of friction at each contact surface between the rack housing 82 and the rubber-like elastic body 72 decreases. This makes the rubber-like elastic body 72 more susceptible to deformation, resulting in a larger deflection than intended. This may result in a decrease in the durability of the buffer stopper 7.

[0009] For these reasons, there is a demand for a buffer stopper that can be manufactured at lower cost than conventional ones while also improving durability.

[0010] In order to solve the above problems, a buffer stopper according to one embodiment of the present disclosure is a buffer stopper arranged between a flange portion having a first annular surface extending from the outer peripheral surface of an axially movable shaft, and a protrusion having a second annular surface extending from the inner peripheral surface of a cylindrical housing that accommodates the shaft toward the shaft, the second annular surface being spaced apart from and facing the first annular surface, and comprising: a metal ring in contact with the first annular surface; an annular buffer body provided between the metal ring and the second annular surface and joined to the metal ring; and an annular member provided between the buffer body and the second annular surface and joined to the buffer body, wherein the buffer body comprises a rubber-like elastic material, the metal ring is an annular flat plate, the annular member is spaced apart from the metal ring and is provided radially inward of the buffer body, and the rigidity of the annular member is greater than the rigidity of the buffer body.

[0011] According to the present disclosure, it is possible to achieve improved cushioning performance and durability while reducing costs compared to conventional methods.

[0012] Fig. 1 is a cross-sectional view showing a part of a steering device including a buffer stopper according to an embodiment; Fig. 2 is a cross-sectional perspective view showing a part of the buffer stopper according to an embodiment; Fig. 3 is an enlarged cross-sectional view of a part of the buffer stopper according to an embodiment; Fig. 4 is a characteristic curve diagram of the buffer stopper according to an embodiment; Fig. 5 is a cross-sectional view showing a buffer stopper of a modified example; Fig. 6 is a view showing a conventional buffer stopper; Fig. 7 is an example of another conventional buffer stopper for reducing costs.

[0013] Preferred embodiments of the present disclosure will be described below with reference to the accompanying drawings. The dimensions and scale of each part in the drawings may differ from the actual dimensions, and some parts are shown schematically to facilitate understanding. The scope of the present disclosure is not limited to these embodiments unless otherwise specified in the following description to the effect that the present disclosure is limited.

[0014] 1. Steering Devices Vehicles such as automobiles use, for example, rack-and-pinion steering devices. The steering device includes, for example, a steering wheel operated by the driver, a steering shaft connected to the wheel, a pinion gear coaxial with the steering shaft, and a shaft on which a rack gear is mounted that converts the rotation of the pinion gear into axial movement. The movement of the shaft is transmitted to the wheels via tie rods. As the tie rods oscillate relative to the shafts as the shafts move, the wheels can be turned in any direction. The shafts are housed in a housing.

[0015] Such a steering device is provided with a damper device for absorbing the impact between the shaft and the housing caused by the swinging of the tie rod.

[0016] Fig. 1 is a cross-sectional view showing a portion of a steering device 100 including a buffer stopper 1 according to an embodiment. Fig. 1 illustrates a portion of the steering device 100. Specifically, the steering device 100 has a shaft 3, a tie rod 4, a housing 5, a rack boot 6, and a damper device 10. The damper device 10 includes a flange portion 30, a protrusion 50, and the buffer stopper 1. Note that although the flange portion 30 is connected to the shaft 3 and the protrusion 50 is connected to the housing 5, the flange portion 30 can also be considered to be a part of the shaft 3, and the protrusion 50 can also be considered to be a part of the housing 5.

[0017] The shaft 3 is, for example, cylindrical. A rack gear 35 is provided on the shaft 3 along the axial direction. Note that the "axial direction" refers to the direction along the central axis A of the shaft 3, which coincides with the extension direction of the shaft 3. The rack gear 35 is configured to mesh with a pinion gear (not shown), and converts the rotational motion of the pinion gear into linear motion along the central axis A. Therefore, the shaft 3 is movable in the axial direction. The material of the shaft 3 is, for example, metal.

[0018] The housing 5 is a cylindrical enclosure that accommodates the shaft 3. The housing 5 is fixed to, for example, a vehicle body (not shown). The housing 5 is, for example, cylindrical and extends along the axial direction. The inner diameter of the housing 5 is slightly larger than the diameter of the shaft 3. The material of the housing 5 is, for example, metal.

[0019] The flange portion 30 of the damper device 10 is a stud end attached to the end of the shaft 3. The flange portion 30 is made of, for example, metal. The flange portion 30 has a flange main body 301 and a protrusion 302.

[0020] The flange body 301 is, for example, cylindrical. The outer diameter of the flange body 301 is larger than the outer diameter of the shaft 3. An opening 301D is provided in the flange body 301. The opening 301D is a bottomed hole that opens on the side of the flange body 301 opposite the convex portion 302. A ball joint 40 of the tie rod 4 is housed in the opening 301D. The ball joint 40 is housed in the opening 301D via a buffer material 401. Furthermore, the tie rod 4 swings about the central axis A as the rack gear 35 moves along the central axis A.

[0021] The flange main body 301 also has a first annular surface 30s. The first annular surface 30s protrudes radially outward from the outer peripheral surface 3s of the shaft 3. The "radially outward" refers to a direction perpendicular to the central axis A of the shaft 3 and away from the central axis A. In the following, the direction perpendicular to the central axis A of the shaft 3 and extending from the housing 5 toward the central axis A will be referred to as the "radially inward." Furthermore, the direction perpendicular to the central axis A of the shaft 3 will be referred to as the "radial direction."

[0022] The protrusion 302 is a portion that protrudes from the flange main body 301 toward the shaft 3 and is formed integrally with the flange main body 301. The protrusion 302 is, for example, cylindrical. A recess 3D is provided at the end of the shaft 3, and the protrusion 302 is disposed inside the recess 3D. For example, a female thread is formed on one of the inner circumferential surface of the recess 3D and the outer circumferential surface of the protrusion 302, and a male thread is formed on the other. The protrusion 302 and the recess 3D are screwed together. This screwing connects the flange 30 to the shaft 3.

[0023] The protrusion 50 of the damper device 10 is an annular structure that protrudes radially inward from the inner circumferential surface 5s of the housing 5 and is formed integrally with the housing 5. The protrusion 50 surrounds the outer circumferential surface 3s of the shaft 3. The protrusion 50 is, for example, annular. The inner diameter of the protrusion 50 is slightly larger than the outer diameter of the shaft 3. The protrusion 50 is spaced apart from the flange main body 301.

[0024] The protrusion 50 has a second annular surface 50s. The second annular surface 50s is an end face of the protrusion 50 located on the flange portion 30 side. The second annular surface 50s protrudes radially inward from the inner circumferential surface of the housing 5. The second annular surface 50s faces the first annular surface 30s at a distance.

[0025] The housing 5 is also provided with a storage portion 50H. The storage portion 50H is a space defined by the second annular surface 50s and a portion of the inner circumferential surface 5s of the housing 5 that is closer to the ball joint 40 than the protrusion 50. The storage portion 50H accommodates the flange main body 301 described above. The inner diameter of the wall defining the storage portion 50H is larger than the outer diameter of the flange main body 301. A rack boot 6 is also connected to the housing 5. The rack boot 6 has a cylindrical bellows shape. The tie rod 4 is accommodated inside the rack boot 6.

[0026] The buffer stopper 1 of the damper device 10 is provided between the flange portion 30 and the protruding portion 50. Specifically, the buffer stopper 1 is provided between the first annular surface 30s of the flange portion 30 and the second annular surface 50s of the protruding portion 50. The buffer stopper 1 is provided to reduce the impact between the shaft 3 and the housing 5 caused by the swinging of the tie rod 4.

[0027] 2. Buffer Stopper Fig. 2 is a cross-sectional view showing a part of the buffer stopper 1 according to the embodiment. As shown in Fig. 2, the buffer stopper 1 includes a metal ring 11, a buffer body 12, and an annular member 13.

[0028] The metal ring 11 is an annular flat plate, and in this embodiment, is a circular flat plate. The metal ring 11 is made of metal. Specifically, for example, the metal ring 11 is made of a hot-rolled mild steel plate such as SPHC.

[0029] The buffer 12 is joined to the metal ring 11 by, for example, vulcanization bonding. The buffer 12 is tubular, and in this embodiment, is substantially cylindrical. The length of the buffer 12 along its axial direction is longer than the length of the metal ring 11 along its axial direction. The buffer 12 has elasticity that absorbs shock. The rigidity of the buffer 12 is lower than the rigidity of the metal ring 11. The buffer 12 is made of a rubber-like elastic material. The term "rubber-like elastic material" refers to a thermosetting elastomer such as rubber, a synthetic resin with rubber-like elasticity, and a mixed material containing rubber. A specific material for the buffer 12 is preferably nitrile rubber (NBR) from the viewpoint of high hardness and durability. Furthermore, a material in which carbon black is added to nitrile rubber (NBR) is more preferably used as the buffer 12 material.

[0030] The difference between the inner and outer diameters of the buffer body 12 is slightly shorter than, but may be the same as, the difference between the inner and outer diameters of the metal ring 11. The difference between the inner and outer diameters is the radial length. The occupancy ratio of the buffer body 12 in the buffer stopper 1 is greater than the occupancy ratio of the metal ring 11 in the buffer stopper 1.

[0031] The buffer 12 also has a covering portion 121. The covering portion 121 is a portion of the buffer 12 that covers the outer peripheral surface 111 of the metal ring 11. The inner peripheral surface 112 of the metal ring 11 is not covered by the buffer 12.

[0032] The annular member 13 is joined to the buffer 12 by, for example, vulcanization bonding. The annular member 13 has an annular shape, and in this embodiment, is annular. The annular member 13 is provided on the surface of the buffer 12 opposite the metal ring 11. The annular member 13 is spaced apart from the metal ring 11. From another perspective, the buffer 12 has a portion located between the annular member 13 and the metal ring 11. The annular member 13 is provided on the radially inner side of the buffer 12.

[0033] The occupancy ratio of the annular member 13 in the buffer stopper 1 is smaller than the occupancy ratio of the buffer body 12 in the buffer stopper 1. The occupancy ratio of the annular member 13 in the buffer stopper 1 is also smaller than the occupancy ratio of the metal ring 11 in the buffer stopper 1. The difference between the inner and outer diameters of the buffer body 12 is shorter than the length of the difference between the inner and outer diameters of the buffer body 12. In this embodiment, the difference between the inner and outer diameters of the annular member 13 increases as it moves away from the metal ring 11.

[0034] The rigidity of the annular member 13 is higher than the rigidity of the buffer body 12. For example, the Young's modulus of the annular member 13 is higher than the Young's modulus of the buffer body 12. The material of the annular member 13 is, for example, a metal, a resin, or a rubber-like elastic material.

[0035] The Young's modulus of the annular member 13 is not particularly limited, but is, for example, 100 MPa or more and 1000 MPa or less. The Young's modulus of the buffer body 12 is not particularly limited, but is, for example, 1 kgf / cm ２ ] or more 100 [kgf / cm ２ The Young's modulus of the metal ring 11 is not particularly limited, but is, for example, 10 [GPa] or more and 500 [GPa] or less.

[0036] 3 is an enlarged cross-sectional view of a portion of the buffer stopper 1 according to the embodiment. As shown in FIG. 3, the buffer stopper 1 is disposed between the first annular surface 30s and the second annular surface 50s and is in contact with them. For example, the buffer stopper 1 is press-fitted between the first annular surface 30s and the second annular surface 50s so that the buffer 12 is elastically deformable. In the illustrated example, the buffer stopper 1 does not contact the shaft 3 or the housing 5, but may, for example, be in contact with the shaft 3.

[0037] The metal ring 11 of the buffer stopper 1 contacts the first annular surface 30s. The buffer 12 and the annular member 13 each contact the second annular surface 50s. Specifically, an end face 125 of the buffer 12 opposite the metal ring 11 and an end face 135 of the annular member 13 opposite the metal ring 11 contact the second annular surface 50s. As shown in FIG. 2 , in an unattached state where the buffer stopper 1 is not provided between the first annular surface 30s and the second annular surface 50s, the end face 125 and the end face 135 are continuous and flush with each other without any steps.

[0038] In this buffer stopper 1, the metal ring 11 receives the impact caused by the swinging of the tie rod 4, and the shock absorber 12 is compressed and elastically deformed by the impact received by the metal ring 11. When the flange portion 30 approaches the protrusion 50 and the gap between the first annular surface 30s and the second annular surface 50s decreases, the shock absorber 12 is compressed in the axial direction and expands radially inward and outward by the amount of compression. As a result, the buffer stopper 1 is pressed against the first annular surface 30s and the second annular surface 50s. In this way, the buffer stopper 1 mainly absorbs the impact with the shock absorber 12.

[0039] The buffer stopper 1 configured as described above includes a metal ring 11, a buffer 12, and an annular member 13. The metal ring 11 contacts the first annular surface 30s. The metal ring 11 is an annular flat plate. The buffer 12 includes a rubber-like elastic material, is provided between the first annular surface 30s and the second annular surface 50s, and is bonded to the metal ring 11. The annular member 13 includes a rubber-like elastic material, is provided between the first annular surface 30s and the second annular surface 50s, and is bonded to the buffer 12.

[0040] The buffer stopper 1 has the metal ring 11, which allows it to absorb or cushion loads that cannot be absorbed by the buffer body 12 alone. Furthermore, because the metal ring 11 is an annular flat plate, the metal ring 11 can be constructed as a single member, and it is easier to lower the proportion of the metal ring 11 in the buffer stopper 1 compared to conventional methods. This allows for lower costs than conventional methods.

[0041] Furthermore, the rigidity of the annular member 13 is higher than the rigidity of the buffer 12. Therefore, the surface pressure of the annular member 13 against the second annular surface 50s can be higher than the surface pressure of the buffer 12 against the second annular surface 50s. The annular member 13 is provided radially inward of the buffer 12. This allows the annular member 13 to function as a sealing member that prevents lubricating grease from entering between the buffer 12 and the second annular surface 50s. Therefore, the provision of the annular member 13 can reduce the risk of lubricating grease applied to the shaft 3 leaking radially outward and entering between the buffer 12 and the second annular surface 50s. This improves the durability of the buffer 12.

[0042] If the annular member 13 were not provided, the lubricating grease would penetrate between the buffer body 12 and the second annular surface 50s. In this case, the coefficient of friction between the end face 125 of the buffer body 12 and the second annular surface 50s would decrease. This would make the buffer body 12 more susceptible to deformation, resulting in a larger deflection than intended. This could result in a decrease in the durability of the buffer stopper 1.

[0043] In contrast, in this embodiment, the annular member 13 is provided. This prevents lubricating grease from entering between the buffer 12 and the second annular surface 50s. This reduces the decrease in the coefficient of friction as described above. This prevents the buffer 12 from deforming and causing the amount of deflection to be greater than intended. As a result, the durability of the buffer stopper 1 can be improved.

[0044] Furthermore, as described above, the annular member 13 is spaced apart from the metal ring 11. Therefore, even if the distance between the first annular surface 30s and the second annular surface 50s decreases and the buffer body 12 is compressed in the axial direction, the annular member 13 is prevented from being pinched between the second annular surface 50s and the metal ring 11 and being damaged. If the metal ring 11 and the annular member 13 were connected, the buffer body 12 would be compressed in the axial direction and the annular member 13 would be crushed between the metal ring 11 and the second annular surface 50s and be damaged. Furthermore, because the annular member 13 is spaced apart from the metal ring 11, the buffer body 12 is easily elastically deformed in the radial direction when compressed in the axial direction.

[0045] As described above, the annular member 13 is provided radially inside the buffer body 12. Therefore, the buffer body 12 is in contact with the second annular surface 50s. Therefore, the buffer body 12 can exhibit its cushioning performance more effectively than when the end surface 125 of the buffer body 12 is covered with the annular member 13 and the buffer body 12 is not in contact with the second annular surface 50s.

[0046] Fig. 4 is a characteristic diagram of the buffer stopper 1 according to the embodiment. The horizontal axis of Fig. 4 represents the displacement [mm] of the buffer stopper 1, and the vertical axis represents the load [kN] applied to the buffer stopper 1. The displacement of the buffer stopper 1 can also be considered to correspond to the compressive strain along the axial direction of the buffer 12.

[0047] The characteristic line L1 shown by a solid line represents the buffer stopper 1 of this embodiment. The characteristic line L2 shown by a dashed line represents the buffer stopper 7 of the comparative example in Fig. 7. The buffer stopper 1 of this embodiment has the annular member 13, whereas the buffer stopper 7 of the comparative example does not have the annular member 13. The volume of the buffer stopper 1 of this embodiment and the volume of the buffer stopper 7 of the comparative example are the same.

[0048] The slope of the characteristic line L1 is greater than the slope of the characteristic line L2 of the comparative example. Therefore, the linear region of the characteristic line L1, i.e., the region below the characteristic line L1, is greater than the linear region of the characteristic line L2 of the comparative example, i.e., the region below the characteristic line L2. Therefore, the buffer stopper 1 of this embodiment can significantly increase the amount of absorbed energy, i.e., the maximum compressive displacement, compared to the comparative example. Accordingly, the amount of deflection upon impact can be reduced. Therefore, the buffer stopper 1 of this embodiment can improve the buffering performance and durability of the buffer stopper 1 compared to the comparative example. In particular, the buffering performance and durability can be improved without increasing the volume of the buffer stopper 1 compared to the comparative example.

[0049] If lubricating grease is present between the buffer 12 and the second annular surface 50s, the coefficient of friction of the end surface 125 of the buffer 12 decreases, which is thought to result in increased internal stress in the buffer 12. This is thought to reduce the amount of energy that the buffer 12 can absorb, resulting in a decrease in buffering performance. The buffer stopper 1 of this embodiment can reduce the risk of such a decrease in buffering performance.

[0050] As described above, the material of the annular member 13 is, for example, metal or resin, but it is preferable that the annular member 13 contains resin. When the annular member 13 contains resin, the annular member 13 can be easily formed into any shape.

[0051] When the annular member 13 is made of resin, the material of the annular member 13 is not particularly limited, but is preferably a super engineering plastic such as polytetrafluoroethylene (PTFE) or polyether ether ketone (PEEK). Such materials are preferred because they are particularly durable and impact-resistant. By using such materials, the intrusion of lubricating grease between the buffer body 12 and the second annular surface 50s can be more effectively prevented than when other materials are used.

[0052] Furthermore, it is preferable that the material of the annular member 13 has excellent resistance to lubricating grease. For example, super engineering plastics such as PTFE and PEEK can exhibit resistance to various types of lubricating grease.

[0053] Furthermore, it is preferable that the volume of the annular member 13 is smaller than the volume of the buffer body 12. If the volume of the annular member 13 is larger than the volume of the buffer body 12, the buffer performance of the buffer stopper 1 will be reduced compared to when the volume of the annular member 13 is smaller. Therefore, by making the volume of the annular member 13 smaller than the volume of the buffer body 12, it is possible to suppress a reduction in the buffer performance of the buffer stopper 1 that would be caused by the provision of the annular member 13 reducing the occupancy rate of the buffer body.

[0054] 2, when no load is applied to the buffer stopper 1, the end face 125 of the buffer 12 opposite the metal ring 11 and the end face 135 of the annular member 13 opposite the metal ring 11 are flush with each other. Therefore, compared to when there is a step between the end face 125 and the end face 135, it is easier to achieve uniform surface pressure on the second annular surface 50s over the entire area of ​​the end face 135. This improves the sealing performance of the annular member 13. This effectively prevents lubricating grease from entering between the buffer 12 and the second annular surface 50s.

[0055] 2 and 3, the joint surface 130 of the annular member 13 with the buffer body 12 is inclined with respect to the axial direction. The difference between the inner and outer diameters of the annular member 13 increases in the direction away from the metal ring 11. Therefore, the cross-sectional shape of the annular member 13 is triangular.

[0056] Fig. 5 is a cross-sectional view showing a modified buffer stopper 1A. The difference between the inner and outer diameters of the annular member 13A of the buffer stopper 1A shown in Fig. 5 is constant in the axial direction. Therefore, the cross-sectional shape of the annular member 13A is rectangular. This annular member 13A can also achieve the same effects as the annular member 13 described above.

[0057] However, the annular member 13 of FIG. 3 can increase the surface pressure on the second annular surface 50s compared to the annular member 13A of FIG. 5. With the annular member 13 of FIG. 3, the force on the buffer 12 is applied to the mating surface 130 as the first annular surface 30s and the second annular surface 50s approach each other. As a result, the force applied to the second annular surface 50s at the tip end 139 of the annular member 13 can be increased. This particularly enhances the sealing performance of the annular member 13. This particularly effectively prevents the lubricating grease from entering between the buffer 12 and the second annular surface 50s. This particularly enhances the durability and buffering performance of the buffer stopper 1.

[0058] The cross-sectional shape of the annular member 13 is not limited to the examples shown in Figures 3 and 5. For example, the joining surface 130 may be curved.

[0059] As described above, the buffer 12 has the covering portion 121. The covering portion 121 is a portion that covers the outer peripheral surface 111 of the metal ring 11. By providing the covering portion 121, even if the tie rod 4 swings and the buffer stopper 1 comes into contact with the housing 5, the metal ring 11 and the housing 5 are prevented from coming into contact with each other. Therefore, for example, it is possible to prevent abnormal noise from being generated due to contact between the metal housing 5 and the metal ring 11.

[0060] The damper device 10 including the buffer stoppers 1 and 1A described above can be applied to vehicles as well as transportation equipment and industrial equipment, for example.

[0061] While the present disclosure has been described above based on preferred embodiments, the present disclosure is not limited to the above-described embodiments. Furthermore, the configuration of each part of the present disclosure can be replaced with any configuration that exhibits the same function as the above-described embodiments, and any configuration can be added.

[0062] 3. Supplementary Notes The following aspects, for example, can be understood from the above embodiment and modified examples.

[0063] A first aspect of a buffer stopper, which is a preferred example of the present disclosure, is a buffer stopper arranged between a flange portion having a first annular surface extending from the outer peripheral surface of an axially movable shaft, and a protrusion having a second annular surface extending from the inner peripheral surface of a cylindrical housing that accommodates the shaft toward the shaft, the second annular surface being spaced apart from and facing the first annular surface, and comprising: a metal ring in contact with the first annular surface; an annular buffer body provided between the metal ring and the second annular surface and joined to the metal ring; and an annular member provided between the buffer body and the second annular surface and joined to the buffer body, wherein the buffer body comprises a rubber-like elastic material, the metal ring is an annular flat plate, the annular member is spaced apart from the metal ring and is provided radially inward of the buffer body, and the rigidity of the annular member is greater than the rigidity of the buffer body.

[0064] According to the first aspect described above, since the metal ring is an annular flat plate, it is easy to form the metal ring from a single member, thereby achieving lower costs than conventional methods. Furthermore, since the annular member is disposed radially inside the buffer body and has a higher rigidity than the buffer body, the risk of lubricating grease penetrating between the buffer body and the second annular surface can be reduced. This improves the durability of the buffer body. Furthermore, since the annular member is spaced apart from the metal ring, the risk of the annular member being damaged even when the buffer body is compressed can be avoided. Therefore, according to the first aspect, it is possible to improve buffering performance and durability while reducing costs.

[0065] In a second aspect which is a preferred example of the first aspect, the annular member includes a resin, which allows the annular member to be easily formed into any shape, and provides a buffer stopper with excellent durability.

[0066] In a third aspect, which is a preferred example of the first aspect, the volume of the annular member is smaller than the volume of the buffer body, so that the provision of the annular member reduces the occupancy rate of the buffer body, thereby preventing a decrease in the buffering performance of the buffer stopper.

[0067] In a fourth aspect, which is a preferred example of the first aspect, the buffer further includes a portion that covers the outer peripheral surface of the metal ring. By providing this portion, contact between the metal ring and the housing is prevented, thereby preventing the generation of abnormal noise.

[0068] In a fifth aspect, which is a preferred example of the first aspect, the end face of the buffer opposite the metal ring and the end face of the annular member opposite the metal ring are flush with each other. This facilitates uniformity of the surface pressure of the annular member against the second annular surface. This effectively prevents lubricating grease from penetrating between the buffer and the second annular surface.

[0069] In a sixth aspect, which is a preferred example of the first aspect, the joint surface of the annular member with the buffer body is inclined with respect to the axial direction, and the difference between the inner and outer diameters of the annular member increases in the direction away from the metal ring. In this sixth aspect, the force applied to the second annular surface at the tip of the annular member can be increased. This particularly effectively prevents the lubricating grease from entering between the buffer body and the second annular surface.

[0070] DESCRIPTION OF SYMBOLS 1...Buffer stopper, 1A...Buffer stopper, 2...Buffer stopper, 3...Shaft, 3s...Outer peripheral surface, 4...Tie rod, 5...Housing, 5s...Inner peripheral surface, 6...Rack boot, 7...Buffer stopper, 9...Buffer stopper, 10...Damper device, 11...Metal ring, 12...Buffer body, 13...Annular member, 13A...Annular member, 30...Flange portion, 30s...First annular surface, 35...Rack gear, 40...Ball joint, 50...Protrusion, 50H...Accommodating portion, 50 s...second annular surface, 71...metal ring, 72...rubber-like elastic body, 81...rack bar, 82...rack housing, 83...tie rod, 91...L-shaped metal ring, 93...rubber-like elastic body, 100...steering device, 111...outer peripheral surface, 112...inner peripheral surface, 121...covering portion, 125...end face, 130...joint surface, 135...end face, 139...tip portion, 301...flange main body, 301D...opening, 302...convex portion, 401...buffer material, A...center axis, L1...characteristic line, L2...characteristic line.

Claims

1. A buffer stopper disposed between a flange portion having a first annular surface extending from the outer peripheral surface of an axially movable shaft, and a protruding portion having a second annular surface extending from the inner peripheral surface of a cylindrical housing that accommodates the shaft toward the shaft, the second annular surface being spaced apart from and opposing the first annular surface, the buffer stopper comprising: a metal ring in contact with the first annular surface; a ring-shaped buffer body provided between the metal ring and the second annular surface and joined to the metal ring; and a ring member provided between the buffer body and the second annular surface and joined to the buffer body, the buffer body comprising a rubber-like elastic material, the metal ring being an annular flat plate, the ring member being spaced apart from the metal ring and disposed radially inward of the buffer body, and the ring member having a rigidity greater than that of the buffer body.

2. The buffer stopper according to claim 1, wherein the annular member includes a resin.

3. The buffer stopper according to claim 1, wherein the volume of the annular member is smaller than the volume of the buffer body.

4. The buffer stopper according to claim 1, wherein said buffer body further has a portion covering the outer circumferential surface of said metal ring.

5. The buffer stopper according to claim 1, wherein an end face of the buffer opposite to the metal ring and an end face of the annular member opposite to the metal ring are flush with each other.

6. The buffer stopper according to claim 1, wherein the joint surface of said annular member with said buffer body is inclined with respect to said axial direction, and the difference between the inner and outer diameters of said annular member increases in the direction away from said metal ring.

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